Fanaelialae
Legend
I disagree.Also @Fanaelialae
It is realistic to feel a deep renewal of energy that seems to come from nowhere. These experiences are uncommon but happen. The renewal can be from extensive relaxation to recharge, or oppositely a "second wind" in the midst of daunting challenges. To occasionally switch a short rest as the only way to gain the benefits of a long rest, is narratively verisimilitudinous.
I started this thread in the OneD&D forum to discuss in more detail counting two long rests per encounter.
Sure, you could tie "long rest" benefits to a level. That's not hugely problematic, although, this is a common feature in video games, so you'd probably get complaints that this turns the game into Diablo or something to that effect.
It's connecting resource recovery exclusively to leveling up that's problematic (because it's very meta). My wizard can relax at Club Med for a month, but the only way his hit points and spells are going to recover naturally is if he goes out and murders a few more goblins. That pretty much drop kicks verisimilitude out the window in favor of an heavily gamist mechanic.